Electrical apparatus



April 3, 5 R. WEISSMAN 2,547,511

ELECTRICAL APPARATUS Filed Sept. 22, 1948 2 Sheets-Sheet 1 IN VE N T012 RICHARD WEISS/WIN Q RMQMM A TTOPNE Y Ap 3, 1951 R. WEISSMAN ELECTRICAL APPARATUS 2 Sheets-Sheet 2 Filed Sept. 22, 1948 a e EMF Rte? 3 22 F LU NCQLO F) Ill rulllllllll ||.l M :0 2 L Patented Apr. 3, 1951 ELECTRICAL APPARATUS Richard Weissman, Chicago, Ill., assignor to Nuclear Instrument and Chemical Corporation, Chicago, 111., a corporation of Illinois Application September 22, 1948, Serial No. 50,591

3 Claims.

This invention relates to an electrical apparatus and particularly to an electronic type of counter. While the invention is directed toward a ring type of counter, it is not necessarily limited thereto.

Electronic counters for high speed counting have become well known and are useful for many purposes. While many such counters have been devised and made for 'use in laboratories and locations where skilled and highly trained perv sonnel is available, the field of such counters has expanded beyond such limits. Thus electronic types of counters are useful and advantageous in industrial locations where commercial requirements are important. Such commercial requirements include economy of manufacture, a minimum number of vacuum tubes, circuit simplicity, physical and electrical ruggedness, reliability of operation and high speed of operation.

Prior art counters have various drawbacks which have limited the utility of such counters. Thus some counters are elaborate and characterized by circuit complexity making the counter expensive to make and to maintain. Other counters of a simpler design have been subject to false triggering and thus lack reliability. Furthermore, many counters of the prior art operate the vacuum tubes in a deleterious manner and reduce the operating life of the tubes. A further objectionable feature of prior art counters has been due to the requirement of precision shaping and duration of trigger pulses for operating the same. In many instances, such counting circuits place a heavy load upon'a pulse generator and thus increase the expense and complexity of the pulse generator. A common objection to prior art counters has been their inability to count at high rates of speed.

The invention provides a counter which is simple, and economical in the use of components, is rugged and not subject to false triggering, is operated with a comparatively low pulse power and is not critical of the pulse shape and is susceptible to operation at high pulse repetition rates. The counter embodying the present invention has other advantages and desirable properties all of which will be apparent after the invention has been disclosed The invention will now be described in detail in connection with the drawing wherein Figure 1 is a circuit diagram illustrating the invention and Figure 2 shows the potential characteristics of certain points of the circuit during operation.

The ring counter proper comprises five double unit tubes, TI to T5 inclusive. While each unit of a tube is shown as being a triode, it is possible to use tetrodes or pentodes. Thus tube Tl has cathodes KL and KR, grids GL and GR and anodes AL and AR. The letters L and R are used to designate the left and right units of a tube. For tube T2, the cathodes are indicated by ZKL and 2KR. The remaining electrodes are correspondingly indicated with a numeral 2 as a prefix to refer to the second tube. The higher tubes have their electrodes correspondingly marked.

' Cathodes KL to 5KL inclusive are connected by lead I to grounded bias resistor RKL. Condenser 2 shunts resistor RKL. Similarly oathodes KR to EKR inclusive are connected by lead I to grounded bias resistor RKR, shunted by condenser 2. The ratio of resistances of RKL to RKR is substantially equal to (m.l)/ 1' where n is the number of counter stages. In this case, one resistor is four times the value of the other and it will be assumed that RKL is larger. The shunting condensers should each be large enough to by-pass pulses readily and may be equal.

All L grids are connected to resistors GRL to EGRL respectively. With the exception of GRL, remaining resistors 2GRL to 5GRL inclusive are grounded. All GRL resistors are preferably of equal value. Similarly, grid resistors GRR to EGRR. are all connected between ground and the grids of the right unit of each tube. These resistors are also preferably equal to each other and to the GRL series of resistors.

Between the grid of one tube unit and the anode of the other tube unit for each tube there is connected a resistor. Thus resistor ll) is connected between GL and AR. while resistor Ill is between GR and AL. shunting resistor I9 is condenser II while condenser ll is across resistor l0. Tube T2 has resistors 26 and 2t shunted by condensers Zl and 21 respectively cross-connected. This is continued to tube T5 with resistors 50 and 50' and condensers 5| and 5|.

The AL series anodes are connected through load resistors ARL to 5ARL respectively to wire 3. The AR series anodes are also connected to wire 3 through individual ARR load resistors. A source of suitable potential is connected between wire 3 and ground in the usual manner.

The AR series anodes are also connected to wire 4 through individual condensers CI to C5 inclusive. The input to the system is on wire a.

, Anode SARR is connected through condenser 005i to anode AL. The anode of the right hand unitof one tube is eonnected to the anode of the left hand unit of the next higher tube in the se- 3 ries. Thus AR is connected through CC I 2 to ZAL. Similarly C023 is connected between ZAL and 3AR. Condensers C034 and C045 respectively couple the remaining tubes up to T5.

The AL series anodes are also connected through a series of dropping resistors DR to BDR inclusive to a series of gas tubes NL and NR to 5NL and 5NR inclusive. Thus AL is connected through DR to a common terminal of gas lamps NL and NR. 2AL is connected through 2BR to lamps 2NL and ZNR. This continues to EAL being connected through 5DR to SNL and BNR. The NL series of lamps is connected to common lead NCA while the NR series of lamps is connected to common lead NCB.

Tube T6 is also a double unit tube similar to tubes TI to T5 inclusive. Tube T6 has cathodes BKL and BKR, grids SGL and SGR and anodes GAL and GAR respectively. The cathodes are connected together to grounded bias resistor SKB shunted by condenser EKG.

Grids BGL and BGR are connected to resistors BGRL and GGRR the latter being grounded. These grids are cross connected to the anodes of the tubes by resistors 60 and 6B shunted by condensers BI and GI. Anodes GAL and GAR are connected through dropping resistors EARL and SARR to a common junction for connection to a source of anode potential. Wire 3, also connected to a source of anode potential, may have the same potential source.

Wire NCA is connected to a point on fiARR while wire NCB is connected to a point on EARL. The particular values of these resistors and points of connection may vary depending upon tubes, desired operating conditions and applied potentials.

Resistor GRL has its lower terminal connected to the lower terminal of EGRL and the two are connected to grounded switch ST, normally closed.

The last tube, T1, is a double unit tube and is a double diode. This tube may be a triode like the others for the sake of uniformity and may have grid and anode connected together as a diode. Such an expedient is well known. Tube T? has cathodes 'IKL and lKR connected together to wire 1 going to an intermediate point on resistor 5ARL. Anodes 'IAL and TAR are connected respectively to anodes GAL and BAR.

The operation of the counter will now be de scribed. The counter may be set to a zero starting position by momentarily depressing switch ST. This switch is normally closed and in this condition provides a connection to ground for GRL and BGRL. Upon the momentary opening of this switch, the positive potential present at the anode of GTE will be impressed through resistor 60 and BGRL upon the control grid of TL and render TL conducting. This will occur irrespective of the previous condition of the other tubes.

By virtue of the values of cathode bias resistors RKL and RKR, only one left tube section can be conducting at one time under conditions of equilibrium. It is possible that when the system is going through an operating cycle, such as when a negative trigger pulse occurs or when switch ST is depressed, that more than one left tube unit may be conducting for a very short time. However, when conditions have become stable the cathode bias resistors for tubes TI to T5 inclusive will only permit one left tube section to be conducting at one time.

It has been found that the ratio of bias resisother tendencies to the contrary.

4 tors may depart from the precise ratio indicated by the formula and instead be fractionally higher or lower. Thus in this instance where n is 5, a ratio of about 3 has been found highly satisfactory.

By keeping the time constants in the anode and grid circuit low, the period of instability during which the tubes are changing their condition may be made very short, of the order of a fraction of a microsecond. This time will be substantially less than the duration of a trigger pulse or the time during which switch ST is open when starting.

When tube section TL becomes conducting or is on, tube sections 2TL to 5TL will therefore be nonconducting. The bias on the cathode responsible for this condition will predominate over all Conversely, TR will be nonconducting and remaining sections 2TR to 5TR will be conducting. The counter is now ready for operating and is in condition to be triggered by negative pulses for counting purposes.

Referring to Figure 2, after switch ST has been opened, the potential at AL will be low while the potential at GL will be substantially the same as the cathode potential. grid potential cannot rise above that of the oathode since the tube will be conducting heavily. Hence the potential of GL will be at its maximum. The potential at AR will also be at its maximum. For the time being, the operation of T6 and T! will not be considered.

Now assume that a series of negative pulses are provided on wire l, this being shown in the first curve. The pulses are shown as being spaced evenly along the time axis. This however is not necessary and the pulses may occur at any desired intervals.

The first negative pulse coming in on line 4 will encounter coupling condensers CI to C5 inclusive. Since tubes 2TR to 5TR are all conducting or on, it will be apparent that a low resistance path to ground will be provided at tubes T2 to T5 inclusive. Thus at the second tube, T2, the pulse will go from 2AR to 2KR then through condenser Z' to ground. It is assumed that the pulse terminals are between ground and wire 4. Because of the low resistance offered from ZAR to ground, it will be apparent that the pulse amplitude at 2AR will be negligible. The same is true of the remaining tubes. However, tube section TR is cut off and offers a high impedanceto the pulse at AR. Hence the pulse will pass through condenser H to GL and drop the grid of TL below cutolf. This will result in TL cutting out and TR cutting in. At the same time, the negative pulse at AR will also pass through condenser CCI2 and thence through condenser 2| to EGR. This will tend to cut olf 2TR. The tendency'for ZTR to be cut off will be reinforced by the amplifled negative pulse from AR when TR cuts in. The interaction between the left and right sections of a tube will be similar to the action in a multivibrator circuit and needs no detailed description.

The above potential changes are shown in the third curve when the grid potential is suddenly dropped because of the first pulse. It is to be understood that no accurate relationships between the various amplitudes are shown in the drawings. The pips at the beginning and end of any sudden change in potential are well known in circuits subject to steep wave fronts.

Thus after the first pulse has arrived, tube It is assumed, that the section be; on and the. other L- sections will be 011. U pen the arrival or the; second pulses, the. action. will progress with the pulse having. a substantial amplitude at. ZAR, and having: negligible amplitude at the: remaining, anodes: of the R; tube. sections. Thus. as; shown in the second curve, thepotential. at. AR willdip slightly when this tube section is conducting at.v the time that. a pulse reaches it..

It is thus apparent that the negative trigger pulses are efiective only at the two tubes whose conditions are to be changed. At other tubes, the pulse has negligible amplitude and is, completely inefiective. Thus successive pulses will.

cause. the various tubes to change their condi.

tion. It should be noted that the low impedanceprovided across the bias, resistors for the left: and right; series of cathodes functions in a dual manner. Thus for those tubes whose right hand section is conducting and where the pulse is to be ineffective, condenser 2 completes a now impedance path from the anode. Thus as an exanu ple, when tube 2TB is conducting, the path of a, pulse is from wire 4 through condenser C2 through tube 2TB and through condenser 2' to ground. By having condenser 2 large, and since the resistance of 2TB. when conducting is comparatively low, the. major potential drop for the pulse path will be across condenser C2. If however, 2TB is open then the situation is entirely different. The pulse path is from wire 4 through condenser C2 and condenser 2! to grid, ZGL. This. path may be. considered as a number of series connected condensers and it will be found that a major portion of the pulse potential will be. impressed upon grid ZGL.

Another pulse. path is. from wire 4 through condenser C2, through condenser C023 and cone denser 31' to grid 3GB. By having coupling CC23 comparatively large, the amplitude of the negative pulse from wire '4 on grid 3GB, may be made quite substantial. However, it will be noted that the negative pulse for the tube section ZTR, when it goes on, will reinforce the negative pulse going to grid 3GB.

In the above instance where the pulse amplitude at the anode. of a right hand tube section, such as ZAR, is substantial it is due in a substantial manner to the presence of condenser 2'. Thus as far as a pulse is concerned, cathode 2KR is at ground potential. Hence if the pulse path from wire 4 to ground through open tube section 2TB is considered from a voltage dividing angle, it will be apparent that no potential drops are wasted upon the, cathode to ground por tion of the system. It is thus clear that for all pulses, the cathodes are at ground potential and never vary from that. Hence any variationof grid or anode potential is always with reference to a fixed cathode potential. It will also be noted that the two tubes to be changed are affected simultaneously by the negative pulse. Thus in the example given above where ZTR is to cut in and 3TB is to cut out, it will be apparent that the control grids of Z'IL and 3TB are. pulsed negatively at the same time; This means therefore, that tubes T2 and T3 will both chan e their conditions substantially simultaneously rather than successively as has usually been the practice.

When tube section 5TL will be cut in, a succeeding negative trigger pulse will be effective on tubes T5 and T! by virtue 'of coupling condenser CC5I. This makes a closed ring of the counter. If desired however, condenser C651 may be; omitted and other means may be utilized for starting the cycle of operation over again.

The operation. of gas discharge lamps NL to 5NL and NR to 5NR will now be described. When switch ST is momentarily opened, grid GGL will be positively biased. This will render GTL conducting and cut oil BTR. Thus the potential at BAR. will be high while the potential at EAL will be low. In the fourth curve, the relationship between the potentials at AL and NCA via GAR is shown.

It is clear that 'IAL and TAR will be respectively at. low and high potential. The potential of TKL and 'LKR; will be determined by the condition of tube section B'I'L. At starting with switch ST, tube 5TL will be open and 5AL will be at maximum potential. Hence TKL and 'IKR will be at maximum positive potential. This is shown in the fifth curve. As shown in this curve, the cathode potential of T1 will be higher than the low potential at anode 'IAL. Hence ITL is blocked. At the same time the high potential at TAR makes this positive with respect to 1K and tube TTR will therefore conduct.

As stated before, 6TB is out 01f so the anode potential is at maximum value. This is true even though 'I'I'R is conducting and may bleed ofi? some current. Hence the potential at wire NCA will be high. Of tubes TI to T5 inclusive, only TL of the series is conducting when switch ST is operated. Hence, of all the gas discharge lamps, the lowest potential will be at the lower electrodes of NL and NR. It is evident therefore, that the potential difference across NL will be greater than across any other lamp. This potential difference may be such that lamp NL will go on while the remaining lamps will be dark. This is shown in the, fifth curve where the potentials at 5AL, 1K and (AL are shown.

Also in the fourth curve there is shown the potential condition at AL and NCA via GAR. Thus referring to the fourth curve, it will be noted that the potential at AL is low When TL is on and thereafter the potential remains at its maximum value when TL is on". It is evident therefore that the maximum potential across lamp NL exists only during the time that tube section AL is on and tube section 6TB. is off. As will be shown later, this condition only occurs once every ten times.

When a negative trigger pulse arrives and causes ZTL to out in, the maximum potential difierence will now be shifted to ZNL. This will continue until ETL cuts in. When ETL cuts in, the potential at SAL will drop and cause the po-- tential in wire I and cathodes lKL and 'iKR to drop. This is shown by the dotted line in the fifth curve. Inasmuch as tube section 5TL conducts until a succeeding pulse arrives, it will be clear that the potential of the cathode of tube Tl will be low for the time interval corresponding to the time that tube 5TL conducts.

Th (11391) in potential of the cathodes of tube Tl will caus a rush of current from LAB to c th ode 5K. It should be. remembered that EAR is still at high p tential du to the test is op n 0 ofi. The sudden rush of current will drop the potential of BAR and the resulting negative pulse will be transmitted through condenser hi to the grid of ETL to cut ETL 01f. Hence tube T55 will go through a multivibrator cycle with tiTL being now open and ETR being new on. As shown in the fifth curve, when the anode potential at 5TB drops, this will result n the p tenti l at the ode of the diode section drop ing belo t pptential of the cathode. Thus in the fifth curve, the potential conditions of the anode for the left section of tube T1 is shown. It is understood that the potential conditions for the right sec tion are the same but displaced in phase. In any event, it is clear that when tube section ET]; is not conducting that the diode section blocks for that portion corresponding to the section of tube T6 which is conducting.

When a negative pulse arrives to change BTL from conducting to nonconducting conditions, the resulting rise in potential of the cathode for tube T? will not trigger tube T6. Diode Tl has both sections blocked when the cathodes are at maximum potentials and this will occur when tube section TL is off.

Thus as an example, let it be assumed that STL is conducting by virtue of a pulse having just arrived to cut in 5TL. This means that the cathode for Tl will be at a relatively low potential to TAR. The cathodes however, will be positive to lAL so that ITL will be blocked while 'lTR will be conducting. Now if a succeeding pulse arrives at wire 6, tube section ETL will cut out and tube section TL will cut in at the same time. The potential for the cathodes of Tl will rise to maxi mum value. Inasmuch as lTL was previously blocked, the rise in cathode potential will have no effect. However, the sudden blocking of lTR will cause a sudden jump in potential at BAR. This will be communicated to EGL. However, since BTL has been conducting, the positive pulse will have no effect. Thus tube T6 will be triggered only when tube 5TL cuts in and will not be affected by the cut-out of 5TL.

When tube T6 changes its condition, the high potential present in line NCA will change to NCB or vice versa. When tube T6 has changed its condition, the corresponding series of gas lamps will be susceptible to operation. Thus a distinction will be made when TL is on for example, as to whether NL or NR will be lit.

Thus if NL corresponds to zero in a counting cycle, 2NL will correspond to l and so on up to 5NL which will correspond to 4. Thereafter NR will correspond to 5 and this will continue until BNR, is reached which will correspond to 9. Then of course the counting cycle will repeat.

The counting circuit itself comprising tubes TI to T5 inclusive has five stages but obviously may have any desired number of n stages. Each stage consists of two vacuum tube units whose control grids and anodes are cross connected. The additional tubes. in this instance tubes T6 and Tl, increase the flexibility and range of operation of the counting circuit.

By virtue of the invention a rugged counter is provided which is not sensitive to substantial variations of anode and filament potentials. While no cathode energizing means are shown, it is understood that such means are essential. Prior art systems have been sensitive to line voltage fluctuations and have required voltage regulated power supplies. This is not true in applicants case and conventional power supplies common in conventional radio receivers may be used. Furthermore, a system embodying the present invention may be assembled without too much care as to precise values of components, condition of tubes, etc. Thus the RKL and RKR resistors are the most critical and these may vary by 10% from assigned values. Other components may vary more widely. Tube aging in general has little effect on system operation. The system as a whole is not critical of the trigwill be conducting and only one of the right unit will be conducting. In such case, this is accomplished by having the right bias resistor RKR larger than RKL resistor. In such case, it will also be necessary to change the connections from the coupling condensers CI to C5 to the left tube unit anode respectively. Also, the coupling condensers between anodes, such as for example CCI2, will be between the left unit of the first tube and the right unit of the second tube. In other words, each tube will have the two units reversed.

What is claimed is:

1. A counting circuit comprising n cascaded vacuum tube stages, each stage comprising left and right tube units forming a pair of vacuum tube units, each unit having at least a cathode, control grid and anode, the grids and anodes of a stage being cross-connected by resistors shunted by condensers, a grounded resistor for each control grid, a grounded bias resistor common to all left cathodes, a grounded bias resistor common to all right cathodes, the left bias resistor being substantially n1 times the right bias resistor and each bias resistor being shunted by a by-pass condenser, load resistors for each anode going to a common terminal for connection to a grounded source of high potential, an interstage condenser directly coupling the right anode of a stage to the left anode of the next succeeding stage, a coupling condenser from a common input line directly to each right anode, the cross-connections for each stage permitting only one tube unit of a stage to be conducting at any one time and the bias resistors permitting only one left tube unit to be conducting at any one time to provide an odd stage condition whereby a negative trigger pulse at the input line will result in successive stages being in an odd condition.

2. The counting system according to claim 1 wherein a pair of voltage responsive indicating means for each stage have one terminal of each connected to the anode of the left tube unit of each stage, to provide left and right indicating means for each stage, a common connection for the other terminal of the left indicating means for all stages, a common connection for the other terminal of the right indicating means for all stages, and means operated by the nth stage for alternately impressing a high potential on said common connections, said high potential having such a value that when a left tube unit is conducting the reduced potential at such anode and the high potential at one of the two other aforementioned other terminals will result in a sufficient difference of potential across an associated indicating means to operate the same whereby said n stages may go through two cycles of operation for one complete cycle of operation of the indicating means.

3. The system according to claim 1 wherein each left anode has connected thereto the common terminal of two voltage responsive indieating means to provide a left and right indicator for each stage, a common connection for the other terminals of the left indicators, a common connection for the other terminals of the right indicators, an additional double unit tube stage having the control grids and anodes crossconnected and having grounded resistors for the control grids, load resistors for the anodes of the added stage, a connection from the left indicator common connection to one of the load resistors of the added stage, a connection from the right indicator common connection to the other load resistor of the added stage, and means for deriving a trigger pulse from the nth stage to trip the added stage so that the left unit of the added a stage is conducting when the counting circuit is going through one complete cycle and the right unit of the added stage is conducting when the counting circuit is going through a succeeding complete cycle, the potential in the common connections for the left and right indicators being alternately raised or lowered depending 7 10 upon the condition of the added stage and when raised being sufficiently high to operate a voltage responsive indicating means at the one stage of the n stages where a left tube unit is conducting.

RICHARD W EISSMAN.

RhW'QRENCES CITED The following references are of record in the fife of this patent:

UNITED STATES PATENTS Number Name Date 2,310,105 Michel Feb. 2, 1943 2,407,320 Miller Sept. 10, 1946 2,436,963 Grosdofi Mar. 2, 1948 2,462,275 Morton Feb. 22, 1949 OTHER REFERENCES High-Speed N-Scale Counters: T. K. Sharp less; Electronics, March 1948,pp. 122-125. 

